n. the branch of pure mathematics dealing with the theory of numerical calculations

Etymologies

Middle English arsmetike, from Old French arismetique, from Medieval Latin arismetica, alteration of Latin arithmētica, from Greek arithmētikē (tekhnē), (art) of counting, feminine of arithmētikos, from arithmein, to count, from arithmos, number.

(American Heritage® Dictionary of the English Language, Fourth Edition)

From Middle English arsmetike, from Old French arismetique, from Latin arithmetica, from Ancient Greek ἀριθμητική ("counting") (τέχνη ("art")), from ἀριθμός ("number"). Used in English since 13th Century. (Wiktionary)

Examples

Hollyhock sat down to the midday meal at The Garden in exceedingly low spirits, but her father had now got through what she called his arithmetic, and was full of mirth.

Moreover, whilst Peano arithmetic is axiomatizable, there is a particular model of Peano arithmetic, whose theory is typically referred to as Number theory, which Godel demonstrated to be undecidable and non-axiomatizable.

If Walstreet reform dies or is weakened to no effect, this simply means Congress chose bribes over doing what they know our national security should be obligating them to do, what anyone with a little education in arithmetic and half a conscience can figure out.